8391994477 has 4 divisors (see below), whose sum is σ = 8392348636. Its totient is φ = 8391640320.

The previous prime is 8391994447. The next prime is 8391994489. The reversal of 8391994477 is 7744991938.

8391994477 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 7744991938 = 2 ⋅3872495969.

It can be written as a sum of positive squares in 2 ways, for example, as 8037839716 + 354154761 = 89654^2 + 18819^2 .

It is a cyclic number.

It is not a de Polignac number, because 8391994477 - 2³¹ = 6244510829 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8391994417) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 138774 + ... + 189847.

It is an arithmetic number, because the mean of its divisors is an integer number (2098087159).

Almost surely, 2^8391994477 is an apocalyptic number.

It is an amenable number.

8391994477 is a deficient number, since it is larger than the sum of its proper divisors (354159).

8391994477 is a wasteful number, since it uses less digits than its factorization.

8391994477 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 354158.

The product of its digits is 13716864, while the sum is 61.

The square root of 8391994477 is about 91607.8297799921. The cubic root of 8391994477 is about 2032.1467318305.

The spelling of 8391994477 in words is "eight billion, three hundred ninety-one million, nine hundred ninety-four thousand, four hundred seventy-seven".